The International Telecommunication Union (ITU) is very demanding for the performance of the next generation mobile communication system of International Mobile Telecommunications-Advanced (IMT-Advanced), for example, regarding the maximum system transmission bandwidth up to 100 MHz and peak rates of uplink and downlink data transmission up to 500 Mbps/Hz and 1 Gbps/Hz, and also very demanding for an average spectrum efficiency and an edge spectrum efficiency of the system.
In order to accommodate the IMT-Advanced system, the 3rd Generation Partner Project (3GPP) has proposed in its next generation mobile cellular communication system of Long Term Evolution (LET)-Advanced the use of a technology of distributed antennas to improve the performance of the system. The technology of distributed antennas refers to that antennas are distributed uniformly in a geographical area and all of the antennas are connected with a central controller through transmission lines, e.g., optical fibers, etc., so that the distance between each pair of distributed antennas is generally far above ten times the wavelength of a carrier. The central controller controls an antenna transmitting a signal to a user equipment at a time and receives a signal originated from a user equipment. FIG. 1 illustrates a scenario of downlink transmitting data at a moment of time T. At the moment of time T, the central controller selects three distributed antennas for transmission of data from a base station to a user equipment
The technology of distributed antennas is considered in the 3GPP LTE-Advanced as a rather promising multiple antenna technology to improve the throughout and spectrum utilization factor of a dense cell system and has become a hot area of research in the LTE-Advanced. Distributed antennas can improve the capacity and cell edge transmission efficiency of a system, avoid inter-cell interference and improve the overall performance of the system. In an existing communication system, however, there has been a lack of an established specific solution to a design of distributed antennas.